A commercially available toaster is generally operated in the following manner. A handle of the toaster is manually pressed to move a sliding rack and a toast rack, which carries the bread, downwards to the bottom of a groove. At this time, a circuit is turned on through a switch, and windings of an electronic timer are powered on to render a ferrous piece to be attracted. The handle, the sliding rack and the toast rack are retained in their original positions, and heaters are powered on to toast the bread. After the bread is toasted for a predetermined time set by the electronic timer, the windings of the electronic timer are powered off, and the ferrous piece is thereby released. As a result, the sliding rack, the handle and the toast rack are driven together with the bread to move upwards to their normal positions under a pulling force of a spring. However, the structure of the conventional toaster has some disadvantages. For example, if the resilient force executed by the spring of the toast rack is too strong, a relatively small bread slice will be flicked up into air; and if the resilient force executed by the spring is too weak, a relatively large bread slice will fail to be elevated to its normal position, or a small bread slice will fail to be elevated high enough to take the toasted break out. Consequently, an automatic toaster has been provided, in which a motor is employed to drive a sliding rack to move upwards and downwards. However, the motor in this structure needs to be activated manually, and the toaster fails to automatically identify whether the break is placed into the toast rack.